1. Field of the Invention The present invention relates to a two-dimensional solid state color imaging system and, more particularly, to a solid state color imaging device which enhances resolution.
2. Description of the Prior Art
A single plate solid state color imaging system, having a two-dimensional solid state imaging panel, must have a color analyzing function for analyzing at least three colors. A color mosaic filter is normally disposed on the imaging panel so as to perform the spatial sampling. The color mosaic filter is generally constructed to produce a red color signal (R), a green color signal (G), and a blue color signal (B). The color mosaic filter array must be determined so that a high resolution is ensured.
In the color television system, the bandwidth of the color difference signal is selected narrower as compared with that of the luminance signal because the human beings can not recognize the color at the fine portion of the image. Thus, the color mosaic filter array is preferably designed so as to reduce the resolution of the color signal, and instead enhance the resolution of the luminance signal. Of the three color signals (R), (G) and (B), the green color signal (G) most effectively influences the luminance signal. Therefore, several color mosaic filter arrays have been proposed, in which the green filter ratio is greater than the red or blue filter ratio.
Further, a control circuit related to the above-mentioned color mosaic filter array has been proposed, which includes a one line (1H) delay circuit for ensuring clean imaging. However, the conventional control circuit can not ensure a clean imaging when the object has a great brightness variation along a vertical line. This is caused by the spurious signal. More specifically, the conventional system does not have high resolution in the vertical direction.
In order to minimize the generation of the spurious color signal, the engineering group of the present inventors has proposed a novel control system wherein a vertical contour signal is added to an interpolation signal (1H delayed signal.) Examples of the novel control system are shown in, for example, Japanese patent publication (Tokkaisho) No. 58-90884 (laid open on May 30, 1983) or Japanese patent publication (Tokkaisho) No. 58-99083 (laid open on June 13, 1983). However, the control system proposed in the above-mentioned Japanese patent publications is not suited for the practical use because the system power consumption is relatively high when the CCD delay line is employed. Further, there is a possibility that undesirable color mixing takes place in the above-mentioned system.